A mate of mine has been having a problem with his PC. IT'll boot and run for so long but then resets itself. It has been running SuSE 9.2 and later 9.3 as well as Win XP. This behaviour can happen whichever OS is being used. A virus has been eliminated from the equation. I suspect it his power supply simply not being up to the task but a dodgy motherboard has also been put forward as a possibility. So, please can I have some opinions? This is the layout as far as I know.

The quality of the PSU is more important than any alleged maximum output. The cheap PSUs usually supplied with computers or cases tend to brown out after a while, causing just this sort of problem. Stick with a good quality, branded power supply. I use an Enermax 350W PSU that has powered more than you list with no problems whatsoever.

"Insanity: doing the same thing over and over again and expecting different results." (Albert Einstein)

Thanks guys. He does power a few USB peripherals but at the time I don't know what. Nelz, you could well be right about quality. After a nights sleep a couple more things have occurred to me. It could be a BIOS issue whereby his BIOS is shutting down the CPU when it gets to a certain temperature. Or it could be thermal creep. Whatever it is, this is going to be one of those real puzzlers. I think he is going to be trying a mate's motherboard sometime today as this other guy has the exact same mobo as he does. Very useful of course and not a luxury we all have access to.